The invention relates to a mixing apparatus for an automatic beverage dispenser and particularly to an apparatus for mixing a liquid with a powder or other liquid such as in a coffee or tea dispenser.
Mixing devices are known wherein as seen from FIG. 1 a mixing beaker C and D is provided for receipt of the liquid and powder, and a stirrer housing B is mounted below it. A discharge spout A is located at the bottom of the stirrer housing. Typically, the stirrer has one or more blades E secured to the shaft of an electromotor F contained in a separate motor housing. This housing is assembled with the stirrer housing by means of a twist-lock connection including an interposed seal. A second seal is provided where the motor shaft leaves the motor housing to seal the motor housing against the ingress of liquid. A disadvantage of the known device is that even with these seals, leakage occurs after a certain period of use, particularly where the motor shaft leaves the housing. This leads to oxidation, seizing of the shaft, and burning of the motor.
Further, the apparatus must be cleaned often because it is very important to maintain hygiene in automatic dispensers, especially for hot beverages. Therefore, the mixing beaker, the stirrer housing and the discharge spout have to be formed so that they may be disassembled. Generally, it is not possible to disassemble the stirrer from the motor shaft so that the stirrer itself cannot be cleaned very well. Disassembling the stirrer housing from the motor housing requires some effort because of the seal, which will also wear more quickly because of repeated disassembly. This means that the maintenance work is labor intensive.
An automatic beverage dispenser is also known from DEA No. 2401001 having a mixing beaker, the lower end of which constitutes a stirring housing. The drive motor is mounted on a bracket fixed to the dispenser housing so that the motor is positioned above the mixing beaker, and the motor shaft extends through a cover provided on the beaker. To clean the device the bracket may be removed together with the motor and the stirrer provided that the cover is simultaneously removed. Nevertheless, due to the connection with the motor and its current terminals, cleaning the stirrer is onerous. This automatic beverage dispenser is not very compact due to the fact that the motor is positioned over the mixing beaker.
A stirring device having a rotating stirrer is known per se from EPA No. 0,127,970, corresponding to U.S. Ser. No. 502,619 now U.S. Pat. No. 4,465,377.
A stirrer having a resilient mixing fin incorporating a permanent magnet is known per se from GB-2,069,355A.